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Analog Tachometer PC Mod 222

greenape147 writes: "BurnOutPC has this review of a tachometer modification for your PC. The tachometer, made and sold by Xoxide, works via the serial port and displays the CPU utilization in RPM's! The classical look of this external tachometer is really nice to see after the "window phase" everyone seems to be going through. Not to mention the fact that analog meters are so fun to watch. Currently supported in Windows NT/2000/XP, a GNU/Linux driver is in the works."
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Analog Tachometer PC Mod

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  • Title says it all. I won't buy it unless I can reconfigure it and or use it other operating systems.
    • I suspect it isn't that difficult of a protocol to reverse engineer.
      Would be neat to do different things with it though, like bandwidth monitoring or use it as an actual tach for racing games.
    • I was considering making an analog system occupancy meter months ago. It would be really easy too, through the parrallel port.

      Periodically write the occupancy to the parallel port, which could have a super-simple (tm) R2R digital to analog convertor (appropriately built for the low voltage requirement) hooked up to an analog meter.

      Last time I was experiementing with lpt ports, 10 years ago, the data was held on those lines until the next byte comes through, so no latch should be required.

  • Cheating? (Score:4, Funny)

    by Lord Puppet ( 300347 ) on Friday March 15, 2002 @08:56AM (#3167472)
    When you want to sell the computer, is there a way that you can cheat and roll back the tachometer?

    "Oh, this baby's practically brand new..."
    • A tachometer measure revolutions per minute(rpms) you're thinking of the odometer (which is part of the spedometer 90+% of the time), which measures miliage.
      • How bout an 'odometer'? You can tell exacly how much use a used computer has seen.
  • by Anonymous Coward on Friday March 15, 2002 @09:04AM (#3167495)
    This is pretty cool product, but I have these visions of computer geeks, who as a group can barely manage to use a fork without injuring themselves, trying to cut holes in PC cases with power tools and horribly maming themselves.

    What they really need is a miniature version that fits into a 5.25" drive bay, without the need for major case surgery.

    • Not all geeks are.. well.. geeks. Here in crappy ole Iowa, we recently had our first really big lan party. I saw ALOT of case mods. When I talked to the kids that had done the mods, most of them didn't know what linux was, and couldn't do much with their box other than word proccessing, play quake, and IRC/IM. *shrugs* The world changed somewhere along the line.
    • You ain't kidding me.

      As somebody who has his own tablesaw, power drill, anvil (I do armorwork), etc, it amuses the heck out of me every time I read the "modboy" sites.

      You can always tell them - they're the ones that include four pages at the start on how to use a Dremel. A DREMEL! It's just a dremel, you just -use- it! ;)
  • If this means what I think it does, I'm going to have to bump up the idle of my Windows machine just like I did in my Honda. It just kept dieing when nothing was happening...

    Or would it be the other way around, and I'd redline every time the BSOD pops up? Maybe thats when I miss a gear, I know that messes up my RPM's big time.
  • What I can see of the website, it looks dreadful, but that could be because of the gazillion mySQL errors he's got plastered all over the page. Very unprofessional looking. Looks like his config can't handle more than a few database connections.

    Anyone get a mirror ?

  • Schweete! (Score:4, Funny)

    by Chuqmystr ( 126045 ) on Friday March 15, 2002 @09:06AM (#3167506) Homepage
    But when will they come out with those little tripple-gang under-dash mounting gauge thingies that were so prevalant in POS pickup trucks and Cameros all throughout the '70s and '80s? And just what would they measure? CPU and case temp and voltage? What's next, Pep Boys and Napa Auto stores end up with a cheesy PC hop-ups isle? Oh the humanity!

    /sbin/fsck -U micro$oft

    • It would actually work: use a thermal probe to actually hook up the temperature guage, hook the voltage guage up to the +12V on the power supply (but it would be very boring on a good power supply, so maybe you should hook it up to a drive light or something). Not sure what to do with oil pressure. Maybe sound volume to speakers?

      I think this would be a good use for those "Tokyo-by-night" guages, with LEDs instead of moving needles. That way you wouldn't hear the sound of needles beating against the stop post when the values fluctuated...

  • Gah! (Score:3, Funny)

    by Neon Spiral Injector ( 21234 ) on Friday March 15, 2002 @09:06AM (#3167507)
    So what does this have a big assed shift light, even though you're driving an automatic transmission? There are enough "riced" out cars around now. Leave the computers alone. This in no way adds performance.

    Add a turbo or nitrous oxide, overclock or supercool. Not these useless mods.

    P.S. It is RPM, not RPMs, and expecially not RPM's.
    • by scorcherer ( 325559 ) on Friday March 15, 2002 @09:13AM (#3167527) Homepage
      $ rpm -qa|wc -l

      Dunno about the rev/min, but my PC has 573 RPMs.

    • RPM's is more correct that RPMs, but yeah both are wrong. - J
      • RPM's is more correct that RPMs, but yeah both are wrong.

        If you're going to be a grammar/spelling Nazi, at least get it right. "RPM's" is a possessive form which doesn't make any sense at all in this context. "RPMs" is a plural form...still incorrect in this context, but at least it doesn't shout "ignoramus" as loudly as "RPM's."

    • by M-G ( 44998 )
      Thank you!

      RPM = Revolutions Per Minute

      The plural is built in, thus no need to tack a "s" on the end.
    • P.S. It is RPM, not RPMs, and expecially not RPM's.

      Agreed, Commander Pedant.

      And with baseball season coming up, you should be starting up your compaign to get all members of the press and game announcers to remember that Runs Batted in are RBI, not RBIs (and "expecially" [sic]) not RsBI!

  • by Niles_Stonne ( 105949 ) on Friday March 15, 2002 @09:10AM (#3167520) Homepage
    I thought that this would be a rather interesting project to do, but never really got around to making one.

    On Windows something like this is quite simple, as all of the information is available in HKEY_DYNAMIC_DATA (think that's the one). A driver for it would simply need to poll the value(s) of interest and output them to the serial port.

    On the hardware side of things a simple D/A converter could be used to convert the data to a position for the gauge. Perhaps add some memory or a random function to it so that it would maintain a level or have a nice little "bounce" to it.

    Note that ANY dynamic information could be displayed on it, not just processor usage. I thought about getting one of those old rotary switches and mounting it next to the guage, allowing me to select different things to watch on it. After all, processor useage on my system is rather unexciting - it's been pegged at 100% for over the last year. You could track disk useage, netword throughput(really useful), or any number of other values. For a listing of them look in the "Performance Monitor"(?) application on windows 9x/Me.
    • On Linux something like this is quite simple, as all the information is available in /proc/stat (with per-cpu information for SMP boxes). A driver for it would simply need to poll the value(s) of interest and output them to the serial port. :)
    • I believe tachometers work by getting a 12v pulse from the distributor every time cylinder 1 fires. So all you need to do is up the voltage from the serial port a little and send bits at a frequency proportional to the CPU usage.

      I have a spare tachometer in my closet actually, so maybe I will give it a try myself...


      • I believe tachometers work by getting a 12v pulse from the distributor every time cylinder 1 fires. So all you need to do is up the voltage from the serial port a little and send bits at a frequency proportional to the CPU usage.

        If it's RS-232, a serial port should be spitting out a 12V (±12V, actually) signal already. IIRC, a serial signal can go up to ±30V.

      • It's been a long while since I looked into (or cared about) hooking up a tach, but I'm pretty sure it gets a parallel feed of the pulse stream from the points (or electronic equivalent) to the coil primary. In other words, it gets a pulse every time that any plug fires (or misfires, for that matter).

        I can't remember if the crankshaft makes one turn or two for every rotation of the distributor but either way the faster the engine is turning the more pulses per unit of time. These pulses are fed to a capacitor which smoothes them out into a "steady" DC which rises and falls as engine speed does.

        The tach is basically a DC voltmeter that reads that voltage level on the capacitor. Some tachs have a switch or jumper to change capacitors or change the resistance in a resistor-capacitor combination so that you can set them for either an 8 cylinder or 6 cylinder engine (for 4 cylinders set it for 8 and divide the reading in half).

    • no d/a needed all tachometers that are electronic look for pulses... 1 pulse = 1 rpm.

      just increase the rate of your pulses out the port (parallel port would be a better use, or a pic on the serial port generating the pulses based on a binary number so you dont need to use 30% of the processor to display useless information.)

      this is very easy to anyone that would want to do it under linux and can program a 16f84 Pic.
    • CPU utilization is only in HKEY_DYN_DATA for Windows 9x/Me. When you get to WinNT/2K/XP the interfaces are totally different and accessed through a complex HKEY_PERFORMANCE_DATA pseudo registry key.
  • This could start a whole new line of pc monitoring tools.

    How about a cpu temperature gauge for overclockers.
    A cpu odometer to give a running tally of exactly how many clock cycles it has done over its lifetime.

    Coming soon to a ThinkGeek ad near you.

    • How about a cpu temperature gauge for overclockers.

      Or just Athlon owners who live someplace warm.

      A cpu odometer to give a running tally of exactly how many clock cycles it has done over its lifetime.

      That would be cool. I'd estimate normal workplace use at 1GHz * 9 hours * 1% average usage * 260 days =~ 850 Gcycles/yr. So you'd probably want to measure it in Mcycles, so you can see the numbers move.

    • Windas users can get a mouse odometer [] that measures how far your mouse has travelled in whatever units you chose, as well as measuring things like how far your mose has climed various famous tall landmarks. Fun for a while.

    • One of my older systems [] had a pretty cool temp and fan monitor availible here [] and probably many other places
    • This could start a whole new line of pc monitoring tools.

      (Ok, I just want to say, I think hooking up analog gauges is a neat idea, and I wholeheartedly approve of the "riceboy" mentality. With that out of the way...)

      None of this stuff is really new. A shitload of monitoring tools like this, have already been thought up and implemented. People why are interested in these sort of things, should look into getting something like a Matrix Orbital LCD or VFD [www.matrix-orbital] (or one of their competitors) hooked up to a serial port, and the lcdproc server software [].

      lcdproc clients have been written for all kinds of things, and idle monitors, temperature displays, etc are all old hat. Last year, I had a very embarrassing incident where my home fileserver's RAID5 was running in degraded mode for 6 months(!) before I noticed, because I never bothered to read logs (just goes to show what a shitty admin I am). So I thought, "never again" and darn near effortlessly wrote a little python program that displays my RAID status on the box's VFD. If my one of my RAID's partitions ever goes out again, then the usual "RAID Ok" that flashes on the front of my box every few seconds, will be replaced with something scary-looking, and I'll know.

      LCD/VFD displays are a lot more versatile and general-purpose than analog stuff, the sky's the limit to what you can do with these things, and lcdproc makes them so easy to program. Every box should have one! :-)

  • by Frothy Walrus ( 534163 ) on Friday March 15, 2002 @09:22AM (#3167548)
    since drivers deal with the kernel and not userspace apps, RMS can keep his grubby little mitts of this one. i'd call it a "Linux" driver.
  • Fluctuation (Score:4, Interesting)

    by 1984 ( 56406 ) on Friday March 15, 2002 @09:26AM (#3167557)
    Erm, wouldn't this thing be sat there twitching the whole time?

    CPU usage fluctuates from near zero to 100% depending on what your box is up to, and a subsecond basis. Surely this'd only be good for a machine with a fairly constant load?
    • How about averaging it over several seconds? That's what uptime(1) does.

      If you did, like, 5 or 10 seconds, you'd have a good idea of what was going on without the needle constantly slamming into the limits. (If you think about it, on the lowest level, CPU usage is either 100% or 0% all the time...)

    • I kinda thought that was the whole point: you monitor the load in near real-time, you know, like most CPU monitors. It's not like a speedometer, though it'd be funny to see an odometer attached to the hard drives to see how much life is left on the cylinders! :)
    • I made a cpu load indicator for my server using 10 leds driven by a spare printer port. The code I wrote samples every second then sets the appropriate number of leds. It is setup so the leds stay on for that period. This gets rid of any transients in the cpu load while giving a usefull indication of the load.
  • YMMV (Score:4, Funny)

    by _PimpDaddy7_ ( 415866 ) on Friday March 15, 2002 @09:27AM (#3167558)
    Brings a whole new meaning to the phrase
    "Your Mileage May Vary" now doesn't it? ;)

  • One small flaw... (Score:5, Insightful)

    by Daniel Rutter ( 126873 ) <> on Friday March 15, 2002 @09:36AM (#3167577) Homepage
    I have, of course, just attempted to scam one of these to review on my site [] (most recent pointless case-mod widget review on Dan's Data: this one []), but I can't help but think that there's a basic flaw in the idea.

    Namely - aren't most modders and overclockers running the [] client, or some similar background task, which keeps our CPU utilisation at 100% all the time?

    I could draw a tachometer on the front of this PC, and it'd be 100% accurate :-).

  • by Performer Guy ( 69820 ) on Friday March 15, 2002 @09:37AM (#3167580)
    I want one that goes to eleven.
    • I actually saw Spinal Tap's concert at "Carnegie Fucking Hall," in David St. Hubbin's immortal words. Nigel's guitar had several cool mods, including perhaps over a dozen pickups, exhaust pipes, a speedometer, and a tachometer. That's as much as I could make out with my friend's binoculars, so I don't know if either of the last three did anything...

      Oh, and the show was pretty cool, too. I knew I was in for a good time when I saw the midgets hanging around the back stage door. During the show, they were dressed as delivery guys and brought in the Stonehenge triptych hanging from a wheeled clothing rack, and had David St. Hubbins sign for it mid-song.

  • burnoutpc's tachometer must be going warm now, they've been slashdotted :/
  • to my amazement, when I first started checking toptools, I was able to connect to an HP server and not only see it's load remotely, I could check the CPU temperature.
  • I have to admit - I have *no* knowledge
    whatsoever about car electronics; I don't even
    have a car.

    But I like this idea. Is it possible to build such
    a unit oneself using a standard analog RPM display?
  • by mlas ( 165698 ) on Friday March 15, 2002 @09:51AM (#3167635) Homepage
    • a dipstick that measures free RAM by the depth of brown viscous goo
    • a peep [] plug-in that makes revving noises as cpu cycles increase, and the sound of burning rubber when an app is launched
    • and heck, why not a temperature gauge with a probe attached to the CPU for all you overclockers out there?

    If this keeps up, it won't be long before you start seeing aftermarket replacement chips to improve your computer's performance... oh, wait...
    • and how about a manual transmission shifter box to switch from regular/turbo?
      • Hey, did those older computers with "Turbo" switches actually DO anything? And if so, why wouldn't you want your computer to be running as fast as possible anyway?

        The Turbo button always kinda frustrated me, but it made a light go on and off, so the entertainment from that negated the frustration. :-)
        • Turbo was the normal state (the rated processor speed), and the other setting was slower. This was to allow programs from older computers that used clock cycles as a timing mechanism to work on newer PCs.

          Try playing any 286 game on a Athlon or P3 and you will see the problem.
          • The first couple of turbo switches even made sense--they could drop you back down to the 4.77 clock of the original pc. After that, though,thy tended to just drop you back about 25% from full clock.

            Early games relied on loops and instruction execution for timing--they knew how long something would take, and how much time had elapsed b y where they were in the code. Double the clock, and things ran (roughly) twice as fast, making interactive games hard or impossible.

            I'm not sure this made it into the 286 perio, but if someone figured that that was as fast as desktop/home machines were going to get . . . (i.e., believed the line that the 386 was only for servers, ever . . .)


        • I've always wondered -- if there was a 'Hurry The Fuck Up' button on your computer that you could press to increase the speed, how long would it take before the damn thing was permanantly duct-taped down?

    • Yeah, and how long unti all the ricers start putting huge 10" tachs with 3" shift-lights on their overclocked Celeron 300s?

      "Oh no, redline! Better turn the fan up to high!"
  • Great so I now know when I can shift games without redlining my CPU
  • Of getting one of those add on guage clusters sitting on top of my monitor with a cpu tach, a hours guage (hours of CPU usage), and a temp guage.

    I can finally get back at all those old folks I work with who scoff at me when I say that tweeking your computer is the same thing they did 30 years ago when they messed with their cars.
  • by tom_newton ( 179430 ) on Friday March 15, 2002 @10:22AM (#3167784) Homepage a USB version - advantages being: No serial-port theft (I use all of mine, ta!) and if you have internal USB headers there'd be no shonky cabling out back. Bonanza.

    I wonder if there's a USB device class for this sort of thing?

    ls /dev/usb/wasteoftime/ ;)
  • I dunno... I like to keep my CPU relatively stations... seems even 1 RPM could lead to some rather twisted pins, unless the case was spinning too... and wouldn't any high velocity rotation be bad for the drives? Plus, who would want a spinning computer? ;)
  • Now that we have the CPU tachometer, I wonder if we are any closer to making computer cases look like car dashboards. I'm wondering if it would be possible to:
    • wire a mouse to an odometer to measure miles traveled
    • put a temperature gauge on the case to measure the heat inside
    • use a fuel gauge to measure free disk space

    Next thing you know, Kelley Blue Book [] will be adding computers to their price lists.
  • by Observer ( 91365 ) on Friday March 15, 2002 @10:33AM (#3167828)
    (Warning: contains nostalgia ;)

    Old-timers among us still remember the days when mainframe consoles had lamps indicating the mode the processor was operating in. The old Univac machines used to have a green indicator for "guard mode" (unprivileged user mode) which was typically quite dimly lit but would flash into prominence when a compute-intensive task was active - or when a program was wedged in a tight loop. After you'd worked with one of these machines for a while, you got used to the behaviour of the lamps and of the rows of Blinkenlights on the maintainance panels and took notice if the patterns looked abnormal: quite often this was your first warning that something was going wrong that would need investigation later.

    To return somewhat to the topic, I remember working in the late 1970's on an prototype of the first of these mainframe systems that lacked the customary indicator lamps. I was puzzled for a while by a cheap analog 'Vu' meter balanced on top of one of the cabinets, with a few components soldered to its connectors and a couple of wires trailing back inside: one was clipped to the frame, the other to one of the many wire-wrap pins on the processor back-panel. The meter didn't seem to do anything, but all became clear when I was running a compilation a day or so later: the meter reading went up to 80 percent or so for seconds at a time. Yes, an ingenious engineer had worked out how to fit a guard-mode indicator to the new range machines; sadly, it never made it to the production models and a little piece of computing history came to an end.

    Of course, today I run the Windows task manager so I can tell when the braindead browser on this company-issue PC is wedged and must be killed and restarted. So much for progress.

    • After you'd worked with one of these machines for a while, you got used to the behaviour of the lamps and of the rows of Blinkenlights

      The lamps may be LEDs now, but not much has changed. I've got all my servers in one place next to each other with teh networking gear nearby. All blikenlights in clear view. I run web services, email, etc for a number of folks so I have pretty regular traffic. Its amazing how you quickly associate blink patterns and sounds. I can tell when my raid array (Deathstars) hits a bad sector (which is too often), the network lights tell a lot - I can tell by my switch which server is getting hit the most, etc If I hear an unusual sound from disks or notice odd blink pattersn - I often investigate looking for intruders ;)

      Now if all my web servers had teh triple gauge combos on top showing CPU load, Network load, and Temp - that would be WAY too cool.

      So many ways to waste what little time I have to do stuff like this!

    • Back in my Apple ][ days, there was a gadget that I lusted after. It was an array of LEDs, 16x16 (256 in all), and it was connected to the 8-bit memory bus on the Apple ][. Since you only had 64KB of memory space, each of the 256 LEDs mapped onto a 256-byte chunk of address space. The lights would light up for each access to that chunk.

      It would have been very interesting to watch the lights during, say, garbage collection in BASIC.

      It would still be fun to have something like that on a grander scale, perhaps docked near my CPU meter in my GNOME desktop.

      While I never got the LEDs gadget, I did take an AM radio and set it up on top of my computer, volume turned down low. The RF interference made a distinct sound, which changed pitch when something different happened. If the computer went into an infinite loop, you could hear it. I got tired of the noise, though, so I don't do this anymore.

  • Now my Window$ machine can flash a "Service Engine Soon" light at me. I'll have to put some black tape over it to fix it...
  • by dracvl ( 541254 ) on Friday March 15, 2002 @11:06AM (#3167989) Homepage

    ...the really cute thing about the case mod was the Pac-man eating the reset button and LEDs.

    Check out the picture [] :)

    • ...the really cute thing about the case mod was the Pac-man eating the reset button and LEDs.

      PC Club was selling those the last time I built a couple of machines...they might still have 'em. Wocka wocka wocka wocka...

  • Why not make it go to 10,000 RPM? Then you can tell all of your friends.. "I took it up to 10,000 RPM, dropped the clutch (opened an app) and did a massive burn out!" (BSOD)
  • Guess burnoutpc is having multiple burnouts by the effect of slashdot ...
  • "Are so fun to watch"
    ARRRRRGGGH, thats so *much* fun to watch.
    Or perhaps you meant "their more funner too whatch".
    Anyway, It is a cool hack, but kind of ass backwards. When the rpms are up you should get
    better response. Not likely when the load is up.
  • My computer is a Type R .

    C-X C-S
  • After sending emails around about this here are the best ideas:
    • make a spoiler and airdams out of an old case
    • paint the whole thing neon green
    • slap some vtech stickers all over it
    • replace the drive bay covers with chrome grilles
    • replace the power button with a key start
    • link an engine wav to the tach, as rpms go up the sound get's higher pitched and louder

    Think I found a weekend project next time it's raining.

  • This would be entertaining for anyone who isn't running a distributed computing project (, SETI@home, Folding@Home, etc.). If you are, the thing would be pegged at 100%, all the time, maybe with a slight twitch when you load or terminate an app.

    While you might think it would be cool to have your tach pegged in the far red all the time, my first milisecond-scale reaction would be "Broken gauge", and my second milisecond-scale reaction would be "I just lost all my oil while driving at high speed and my engine will seize up in three... two... one...".

    Either way, I'd have that little viceral moment of panic each time I looked at the thing.
  • The old General Electric 635 (mainframe - late '60s) had an analog MIPS meter for each CPU. It was great fun to watch... and ohh so exciting when it got up near 1 MIP (the maximum it could read).

    BTW... each processor was the size of a bunch of concatenated refrigerators. Memory, in 64MW chunks was in separate similar sized boxes.

    Hey... mod me up... us ancient fogies need all the help we can get :-)
  • If I were to do this on my Linux box,
    I'd have:

    Tach as shown above

    coolant temp gage (for monitoring processor temp)

    Fuel gage for UPS battery life

    Speedometer (for network traffic)

    Now if this was on a windows box,
    The obvious solution would be to replace all gages with idiot lights and fuzzy dice.


  • I built my own remote controlled analog meter using an AC voltmeter from Radio Shack, and an X10 dimmer from (no link needed -- I'm' sure you already have a window open there anyway).

    You can control it remotely from a command-line program and use it to display your web server load, ebay price, whatever. (Hey, it could be a Web Service or maybe even a Gnome widget!)

    See pictures and instructions at
  • Having dabbled with my cars and done lots of work with serial ports, I think I got this one figured.

    When your car is running, the on-board processor (or, if you've got an older model, the points) is firing off a 12 volt signal 4 times per engine revolution (for a 4 cyl). The trigger tells the coil to fire it's juice to the spark plugs. (OK, actually, it causes a field collapse, but that's not important now!) That 12 volt trigger is what a tach normally reads. 1000 RPM = 4000 12 volt triggers per second. 8000 RPM (XOxide's tach max) is 32k triggers per second - closing on as fast as older com ports can go.

    OK, now wire up that trigger connector on the tach to the CTS (or was it RTS?) on a com port. Now a small background process that reads the stat you wanna display then opens the com port the appropriate amount of times per second should do it.

    I think I've got an old tach laying around somewhere...

"If the code and the comments disagree, then both are probably wrong." -- Norm Schryer